Biological Characteristics and Fungicide Screening of Colletotrichum fructicola Causing Mulberry Anthracnose

Abstract

Mulberry is an important economic crop in China that is widely planted and has important edible and medicinal value. Anthracnose, a critical leaf disease, severely compromises the yield and quality of mulberry trees. However, there are many kinds of pathogens causing mulberry anthracnose and it is difficult to control. This study was undertaken to elucidate the biological characteristics of Colletotrichum fructicola, the pathogen responsible for mulberry leaf spot in Zhejiang Province, and to screen out effective fungicides for its management. The biological characteristics of the pathogen were studied using the cross method and spore counting method, while the sensitivity of the pathogen to seven different fungicides was determined using the growth rate method. The findings indicated that potato dextrose agar (PDA) is the optimal growth medium for the pathogen. The pathogen was capable of growing across a temperature range of 5 to 40 °C, with optimum growth observed at 25 °C. Exposure to a 56 °C water bath for 10 min resulted in the death of the pathogen. It was also found to grow and sporulate within a pH range of 4 to 12, with an optimum pH of 7. Under alternating 12 h light and dark cycles, the colonies grew rapidly and produced abundant spores. Among the fungicides tested, 97% carbendazim WP exhibited the best inhibitory effect, with an EC50 (concentration for 50% of maximal effect) value of 0.0242 μg/mL. This was followed by 35% propiconazole SC, which had an EC50 of 0.4180 μg/mL. The fungicidal effect of 25 g/L fludioxonil SSCC was relatively poor, with an EC50 value of 103.0170 μg/mL. This study clarifies the optimal conditions for the growth and sporulation of the mulberry anthracnose pathogen and identifies fungicides with effective inhibitory properties. These findings will provide valuable guidance for field applications and disease management in controlling mulberry anthracnose.